The present invention relates to a radiation image conversion panel.
Radiation images such as X-ray images are widely employed for medical diagnoses. Utilized as a method for obtaining X-ray images is so-called radiography in which X-rays, which have passed through an object, are subjected to irradiation onto a phosphor layer (being a fluorescent screen) to result in visible light, which is irradiated onto a silver salt bearing film, in the same manner as conventional photography, and the resulting film is subjected to photographic processing. In recent years, however, a method has been invented in which images are formed directly from a phosphor layer without employing silver salt coated films.
Said method is described, for example, in U.S. Pat. No. 3,859,527 and Japanese Patent Publication Open to Public Inspection No. 55-12144.
Specifically, a radiation image conversion panel comprised of stimulable phosphors is utilized, and the stimulable phosphor layer of said radiation image conversion panel is subjected to radiation exposure which has passed through the object being diagnosed so that radiation energy is stored corresponding to the radiation transmittance of each portion of said object. Subsequently, the resulting stimulable phosphor layer is sequentially subjected to stimulation employing electromagnetic waves (stimulating light), such as visible light and infrared rays, so that radiation energy stored in said stimulable phosphor layer is released as stimulated luminescence. Signals of the intensity variation of said stimulated luminescence are subjected, for example, to photoelectric conversion to obtain electrical signals. The resulting electrical signals are employed to reproduce visible images on recording materials such as light-sensitive films or display devices such as a CRT.
Accordingly, compared to radiography in which a combination of conventional radiographic films and intensifying screens is used, it is possible to obtain radiation images with ample information, while utilizing much less radiation exposure.
Said radiation image conversion panel comprises a support having thereon a stimulable phosphor layer or a self-supporting stimulable phosphor layer. Generally, said stimulable phosphor layer is comprised of stimulable phosphors as well as binders which disperse said stimulable phosphors and hold them, or is comprised of only coagulated phosphors formed through a vacuum evaporation method or a sintering method. Further, also known are those in which voids in said coagulated phosphors are impregnated with polymers. Further, generally provided on the surface opposite to the support side of the stimulable phosphor layer is a protective layer film such as a polymer film or an inorganic material vacuum-evaporated film.
The stimulable phosphors employed in said radiation image conversion panel are those which result in stimulated luminescence after having been subjected to irradiation of stimulating light after said radiation. In practice, phosphors are commonly employed which result in stimulated luminescence in the wavelength range of 300 to 500 nm utilizing stimulating light in the wavelength region of 400 to 900 nm.
Herein, examples of stimulable phosphors, which have conventionally been employed in said radiation image conversion panel.
(1) Rare earth element activated alkaline earth metal fluorinated halogen phosphors represented by the composition formula of (Balxe2x88x92x, M(II)+X)FX:yA, described in Japanese Patent Publication Open to Public Inspection No. 55-12145, wherein M(II) represents at least one of Mg, Ca, Sr, Zn, and Cd; X represents at least one of Cl, Br, and I; A represents at least one of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, and Er; xe2x80x9cxxe2x80x9d and xe2x80x9cyxe2x80x9d each represent figures satisfying the relationship of 0xe2x89xa6xxe2x89xa60.6 and 0xe2x89xa6yxe2x89xa60.2, respectively. Further, said phosphors may comprise additives as described (a) through (j).
(a) Xxe2x80x2, BeXxe2x80x3, M(III)X3xe2x80x2xe2x80x3, described in Japanese Patent Publication Open to Public Inspection No. 56-74175, (wherein Xxe2x80x2, Xxe2x80x3 and Xxe2x80x2xe2x80x3 each represent at least one of CL, Br and I; and M(III) represents a trivalent metal);
(b) metal oxides described in Japanese Patent Publication Open to Public Inspection No. 55-160078, such as BeO, BgO, CaO, SrO, BaO, ZnO, Al2O3, Y2O3, La2O3, In2O3, SiO2, TiO2, ZrO2, GeO2, SnO2, Nb2O5, and ThO2;
(c) Zr and Sc described in Japanese Patent Publication Open to Public Inspection No. 56-116777;
(d) B described in Japanese Patent Publication Open to Public Inspection No. 57-23673;
(e) As and Si described in Japanese Patent Publication Open to Public Inspection No. 57-23675;
(f) Mxc2x7L (wherein M represents at least one alkali metal selected from the group of Li, Na, K, Rb, and Cs; L represents at least one trivalent metal selected from the group of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and Tl) described in Japanese Patent Publication Open to Public Inspection No. 58-206678;
(g) calcined tetrafluoroboric acid compounds described in Japanese Patent Publication Open to Public Inspection No. 59-27980; calcined, univalent or divalent metal salt of hexafluorosilic acid, hexafluorotitanic acid or hexafluorozirconic acid, described in Japanese Patent Publication Open to Public Inspection No. 59-27289; NaXxe2x80x2 (wherein Xxe2x80x2 represents at least one of Cl, Br and I), described in Japanese Patent Publication Open to Public Inspection No. 59-56479;
(h) transition metals such as V, Cr, Mn, Fe, Co, and Ni, described in Japanese Patent Publication Open to Public Inspection No. 59-56479; M(I)Xxe2x80x2, Mxe2x80x2(II)Xxe2x80x3, M(III)Xxe2x80x2xe2x80x3 and A, (wherein M(I) represents at least one alkali metal selected from the group of Li, Na, K, Rb, and Cs; Mxe2x80x2(II) represents at least one divalent metal selected from the group of Be and Mg; M(III) represents at least one trivalent metal selected from the group of Al, Ga, In, and Tl; A represents a metal oxide; Xxe2x80x2, Xxe2x80x3 and Xxe2x80x2xe2x80x3 each represents at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 59-75200;
(i) M(I)Xxe2x80x2 (wherein M(I) represents at least one alkali metal selected from the group of Rb or Cs; and Xxe2x80x2 represents at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 60-101173;
(j) M(II)xe2x80x2Xxe2x80x22.M(II)xe2x80x2Xxe2x80x32, (wherein M(II)xe2x80x2 represents at least an alkaline earth metal selected from the group Ba, Sr, or Ca; Xxe2x80x2 and Xxe2x80x3 each represents at least one halogen atom selected from the group of Cl, Br, or I, and Xxe2x80x2xe2x89xa0Xxe2x80x3), described in Japanese Patent Publication Open to Public Inspection No. 61-23679; and LnXxe2x80x33 (wherein Ln represents at least one rare earth metal selected from the group of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Xxe2x80x3 represents at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 61-264084.
(2) Divalent europium activated alkaline earth metal halide phosphor represented by the composition formula of M(II)X2.aM(II)xe2x80x22:xEu2+ (wherein M(II) represents at least one alkaline earth metal selected from the group of Ba, Sr, and Ca; X and Xxe2x80x2 each represent at least one halogen atom selected from the group of Cl, Br, and I; and Xxe2x89xa0Xxe2x80x2; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0xe2x89xa6axe2x89xa60.1 and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship and 0xe2x89xa6xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 60-84381. Further, said phosphors may comprise additives as described in (a) through (e) below.
(a) MIXxe2x80x2 (wherein MI represents at least one alkali metal selected from the group of Rb and Cs; Xxe2x80x2 represents at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 60-166379;
(b) KXxe2x80x3, MgX2xe2x80x2xe2x80x3 and M(III)X3xe2x80x3xe2x80x3 (wherein M(III) is at least one trivalent metal selected from the group of Sc, Y, La, Gd, and Lu; Xxe2x80x3, Xxe2x80x2xe2x80x3 and Xxe2x80x3xe2x80x3 each represent at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 221483;
(c) B described in Japanese Patent Publication Open to Public Inspection No. 60-228592; oxides such as SiO2 or P2O5, described in Japanese Patent Publication Open to Public Inspection No. 60-228593; LiXxe2x80x3 and NaXxe2x80x3 (wherein Xxe2x80x3 represents at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No.61-120882;
(d) SiO described in Japanese Patent Publication Open to Public Inspection No. 61-120883; SnX2xe2x80x3 (wherein Xxe2x80x3 is at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 61-120885;
(e) CsXxe2x80x3 and SnX2xe2x80x2xe2x80x3 (wherein Xxe2x80x3 and Xxe2x80x2xe2x80x3 each represent at least one halogen atom selected from the group of F, Cl, Br, and I), described in Japanese Patent Publication Open to Public Inspection No. 61-235486; and CsXxe2x80x3 and Ln3+ (wherein Xxe2x80x3 represents at least one halogen atom selected from the group of F, Cl, Br, and I; Ln represents at least one rare earth element selected from the group of Sc, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), described in Japanese Patent Publication Open to Public Inspection No. 61-235487.
(3) Rare earth element activated rare earth oxyhalide phosphors represented by the composition formula of LnOX:xA, (wherein Ln represents at least one of La, Y, Gd, and Lu; X represents at least one of Cl, Br, and I; A represents at least one of Ce and Tb; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than x less than 0.1), described in Japanese Patent Publication Open to Public Inspection No. 55-12144;
(4) Cerium activated trivalent metal oxyhalide phosphors represented by the composition formula of M(II)OX:xCe, (wherein M(II) represents at least one oxidized metal selected from the group of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Bi; X represents at least one of Cl, Br, and I; xe2x80x9cxxe2x80x9d represent a figure satisfying the relationship of 0 less than x less than 0.1), described in Japanese Patent Publication Open to Public Inspection No. 58-69281;
(5) Bismuth activated alkali metal halide phosphors represented by the composition formula of M(I)X:xBi, (wherein M(I) represents at least one alkali metal selected from the group of Rb and Cs; X represents at least one halogen atom selected from the group of Cl, Br, and I; xe2x80x9cxxe2x80x9d represent a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Application No. 60-70484;
(6) Divalent europium activated alkaline earth metal halophosphate phosphors represented by the composition formula of M(II)5(PO4)3X:Eu2+, (wherein M(II) represents at least one alkaline earth metal selected from the group of Ca, Sr, and Ba; X represents at least one halogen atom selected from the group of F, Cl, Br, and I; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 60-141783;
(7) Divalent europium activated alkaline earth metal haloborate phosphors represented by the composition formula of M(II)2BO3X:xEu2+ (wherein M(II) represents at least one alkaline earth metal selected from the group of Ca, Sr, and Ba; X is at least one halogen atom selected from the group of Cl, Br, and I; and xe2x80x9cxxe2x80x9d is a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 60 157099;
(8) Divalent europium activated alkaline earth metal halophosphate phosphors represented by the composition formula of M(II)2PO4X:xEu2+, (in which M(II) represents at least one alkaline earth metal selected from the group of Ca, Sr, and Ba; X represents at least one halogen atom selected from the group of Cl, Br, and I; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 60-157100;
(9) Divalent europium activated alkaline earth metal hydrogenated halide phosphors represented by the composition formula of M(II)HX:xEu2 (wherein M(II) represents at least one alkaline earth metal selected from the group of Ca, Sr, and Ba; X represents at least one halogen atom selected from the group of Cl, Br, and I; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 60-217354;
(10) Cerium activated rare earth composite halide phosphors represented by the composition formula of LnX3. aLnxe2x80x2X3xe2x80x2:xCe3+, (wherein Ln and Lnxe2x80x2 each represent at least one rare earth element selected from the group of Y, La, Gd, and Lu; X and Xxe2x80x2 each represents at least one halogen atom selected from the group of F, Cl, Br, and I; Xxe2x89xa0Xxe2x80x2; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0 less than axe2x89xa610.0; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), as described in Japanese Patent Publication Open to Public Inspection No. 61-21173;
(11) Cerium activated rare earth composite halide phosphors represented by the composition formula of LnX3. aM(I)Xxe2x80x2:xCe3+ (wherein Ln represents at least one rare earth element selected from the group of Y, La, Gd, and Lu; M(I) represents at least one alkali metal selected from the group of Li, Na, K, Cs, and Rb; X and Xxe2x80x2 each represents at least one halogen atom selected from the group of Cl, Br, and I; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0 less than axe2x89xa610.0; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in JP-A 61-21182;
(12) Cerium activated rare earth halophosphate phosphors represented by the composition formula of LnPO4. aLnX3:xCe3+ (wherein Ln represents at least one rare earth element selected from the group of Y, La, Gd, and Lu; X represents at least one halogen atom selected from the group of F, Cl, Br, and I; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0 less than axe2x89xa610.0; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. 61-40390;
(13) Divalent europium activated cesium rubidium halide phosphors represented by the composition formula of CsX:aRbXxe2x80x2:xEu2 (wherein X and Xxe2x80x2 each represents at least one halogen atom selected from the group of Cl, Br, and I; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0 less than axe2x89xa610.0; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. No. 61-236888;
(14) Divalent europium activated composite halide phosphors represented by the formula of M(II)X2.aMIXxe2x80x2:xEu2+ (wherein M(II) represents at least one alkaline earth metal selected from the group of Ba, Sr, and Ca; MI represents at least one alkali metal selected from the group of Li, Rb, and Cs; X and Xxe2x80x2 each represent at least one halogen atom selected from the group of Cl, Br, and I; xe2x80x9caxe2x80x9d represents a figure satisfying the relationship of 0 less than axe2x89xa610.0; and xe2x80x9cxxe2x80x9d represents a figure satisfying the relationship of 0 less than xxe2x89xa60.2), described in Japanese Patent Publication Open to Public Inspection No. No. 61-236890.
Of said stimulable phosphors, iodide-containing divalent europium activated alkaline earth metal fluorohalide phosphors, iodide-containing divalent europium activated alkaline earth metal halide phosphors, iodide-containing rare earth element activated rare earth oxyhalide phosphors, and iodide-containing bismuth activated alkaline metal halide phosphors are preferable since the materials result in high stimulated luminescence.
The radiation image conversion panel, employing said stimulable phosphors, stores radiation image information and releases stored energy through stimulating light scanning. Therefore, after scanning, it is possible to repeatedly store radiation images so as to be capable of being repeatedly used. Further, contrary to the fact that in the conventional radiography, radiographic film is consumed for every exposure, said radiation image conversion method is more advantageous from the viewpoint of resource conservation as well as economic efficiency, because it is possible to repeatedly utilize said radiation image conversion panel.
In a method employing such stimulable phosphors, it is preferable to achieve durable performance over a long period of time without deteriorating the image quality of radiation images obtained utilizing said radiation image conversion panel.
However, stimulable phosphors, employed to produce said radiation image conversion panel, commonly are very hygroscopic. As a result, when set aside in a room under normal weather conditions, deterioration proceeds markedly over an elapse of time.
Specifically, for instance, when a stimulable phosphor layer is set aside in a high humidity atmosphere, the radiation sensitivity of said stimulable phosphor decreases along with an increase in absorbed moisture. Further, latent images recorded onto said stimulable phosphor layer generally fade along with an elapse of time after radiation exposure. As a result, as the time from radiation exposure to scanning, increases utilizing stimulating light, radiation image signals decrease. Accordingly, when said stimulable phosphor layer absorbs moisture, the rate of image fade increases, whereby reproducibility of regenerative signals is degraded during reading of radiation images.
Therefore, in order to minimize degradation of said stimulable phosphor layer due to moisture absorption, a method is employed in which said stimulable phosphor layer is covered with a moisture resistant protective layer with low moisture permeability so that moisture reaching said stimulable phosphor layer decreases. Employed as said moisture resistant protective layers are a polyethylene terephthalate (PET) film and a metalized film in which a thin layer comprised of metal oxides and silicone nitride is formed through vacuum evaporation.
Known as methods for preparing low moisture permeable protective films are those in which glass plates or high-barrier thick resinous films are employed, and laminated films are employed which are prepared by laminating 2 to 8 films vacuum-evaporated with a thin glass layer comprised of metal oxides and silicon nitride. However, when said methods are employed, problems occur in which the sharpness of the resulting radiation images is degraded due to an increase in thickness of the protective film itself. In order to overcome said problems, Japanese Patent Publication Open to Public Inspection No. 1-131499 proposes that a low refractive index layer, comprised of air, is provided between the protective film and the phosphor layer. Further, Japanese Patent Publication Open to Public Inspection No. 11-249243 describes an embodiment in which a resinous film is employed as the protective film.
Said Japanese Patent Publication Open to Public Inspection No. 11-249243 describes a method for securing the low refractive index layer when a resinous film is employed as the protective layer. However, the practiced constitution of said low refractive index layer is neither illustrated nor suggested.
When said radiation image conversion panel is employed, a laser beam with a high beam convergence is commonly employed as the light source of the stimulating light of a stimulable phosphor plate. Therefore, when scanning is carried out employing a laser beam via the protective layer comprised of a polymer film such as PET, there occur scattering of the stimulating laser beam in the interior of said protective film, and the diffused reflection of the stimulating laser beam between said protective layer and the beam detection device, and in peripheral members. As a result, the stimulable phosphor surface away from the location, wherein the stimulating light is scanned, is subjected to excitation, whereby stimulated luminescence is generated, and as a result, sharpness is degraded. Further, in the case in which said protective layer is not formed on the phosphor plate, problems have occurred in which high sharpness is not obtained due to the diffused reflection of the stimulating laser beam between the phosphor plate surface and the beam detection device, as well as in peripheral members.
Specifically, stretched films, such as polyethylene terephthalate film and polyethylene naphthalate film, exhibit excellent physical properties as the protective layer from the aspect of transparency, barrier properties, and strength. On the other hand, due to their high refractive index, some of the stimulating light incident into the interior of the protective film is repeatedly reflected at the upper and lower surfaces of the film. As a result, stimulated luminescence is generated at positions away from the scanned position due to propagation of said stimulating light, whereby sharpness is degraded.
Furthermore, the stimulating light reflected in the direction opposite the phosphor surface in the upper and lower surfaces of the protective layer is also repeatedly reflected between light detection devices as well as in peripheral members, whereby the stimulable phosphor layer farther away from the scanned position is stimulated to generate stimulated luminescence. As a result, sharpness is further degraded. Said stimulating light is a coherent light of relatively long wavelengths, from red to infrared. Therefore, as long as scattered light as well as reflection light is not sufficiently absorbed, the amount of light absorbed by the interior of the protective film and the space of the interior of the reading device decreases.
Thus, said stimulating light is propagated to relatively distant positions, resulting in the degradation of sharpness. Further, when said polyethylene terephthalate film as well as said polyethylene naphthalate film is employed as the protective layer, problems also occur resulting in unevenness, except for the radiation images of the objects, that is, image unevenness and linear noise which is assumed to have been formed during the production of the protective layer. Japanese Patent Publication Open to Public Inspection No. 59-42500 and Japanese Patent Publication 1-57759 disclose means to minimize said image unevenness as well as said linear noise by increasing the haze ratio of the protective layer. However, when the haze ratio is increased, problems occur in which sharpness is degraded.
Further, in order to minimize such sharpness degradation, it is noted that the thickness of the protective film is preferably decreased to shorten the propagation distance of the stimulating light in the interior of the protective film. However, this method results in small desired effects and by contrast, problems occur in which moisture resistance as well as abrasion resistance is degraded due to a decrease in the thickness of the protective layer. Further, regarding improvement of sharpness, Japanese Patent Publication No. 59-23400 discloses a method in which any of the support, the sublayer, the phosphor layer, the interlayer, and the protective layer of a radiation image conversion panel is tinted with color absorbing stimulating light, while Japanese Patent Publication Open to Public Inspection No. 60-200200 discloses a method in which the adhesive agent layer between the phosphor layer and the protective layer is tinted. However, when the sharpness is enhanced employing said methods, problems occur in which said image unevenness as well as said linear noise is more pronounced.
When said sharpness decreases or said image unevenness as well as said linear noise is pronounced, the radiation image conversion panel, which is utilized for medical diagnoses, results in critical drawbacks.
Accordingly, there has been a demand to solve the problems previously described.
An object of the present invention is to provide a radiation image conversion panel employing a stimulable phosphor, which results in no image unevenness and exhibits excellent sharpness.
Said object of the present invention has been achieved employing items described below.
A radiation image conversion panel comprising a phosphor sheet having a support and a stimulable phosphor layer provided on the support and a protective film covering the stimulable phosphor layer, wherein a transmittance of the protective film for stimulating light to stimulate the stimulable phosphor layer is not larger than 97% and a haze ratio of the protective film is within the range of 5% to 60%.
The radiation image conversion panel of Structure 1, wherein the transmittance of the protective film for stimulating light is within a range of from 97 to 50 percent.
The radiation image conversion panel of Structure 2, wherein the transmittance of the protective film for stimulating light is within a range of from 95 to 80 percent.
The radiation image conversion panel of Structure 1, wherein the haze ratio is within the range of 5% to 50%.
The radiation image conversion panel of Structure 4, wherein the haze ratio is within the range of 10% to 30%.
The radiation image conversion panel of Structure 1, wherein a water vapor transmission rate of the protective film is not more than 50 g/m2 per day.
The radiation image conversion panel of Structure 6, wherein the water vapor transmission rate of the protective film is not more than 10 g/m2 per day.
The radiation image conversion panel of Structure 1, wherein the protective film comprises a stimulating light absorbing layer.
The radiation image conversion panel of Structure 8, wherein the protective film further comprises a first resin layer and a second resin layer and the stimulating light absorbing layer is provided between the first resin layer and the second resin layer.
The radiation image conversion panel of Structure 1, wherein the protective film comprises a thermo-welding resin on a surface, which is in contact with the phosphor sheet.
The radiation image conversion panel of Structure 1, wherein the protective film is provided independently from the stimulable phosphor layer so as to cover the whole surface of the phosphor sheet and the protective film has an outermost layer, which is in contact with the phosphor sheet, and a surface roughness of the outermost layer of the protective film is larger than a surface roughness of the stimulable phosphor layer, wherein the surface roughness is arithmetical mean roughness (Ra) defined by JIS-B0601.
The radiation image conversion panel of Structure 12, wherein the surface roughness of the outermost layer of the protective film is not more than 1.0 xcexcm.
The radiation image conversion panel of Structure 11, wherein a water vapor transmission rate of the protective film is not more than 50 g/m2 per day.
The radiation image conversion panel of Structure 13, wherein the water vapor transmission rate of the protective film is not more than 10 g/m2 per day.
The radiation image conversion panel of Structure 11, wherein the outermost layer of the protective film comprises a thermo-welding resins on surface, which is in contact with the phosphor sheet.
The radiation image conversion panel of Structure 1, wherein the protective film covers a whole surface of the phosphor sheet.